Process for producing acetylenic alcohols



Patented July 29, 1941 PROCESS FOR PRODUCING ACETYLENIC ALCOHOLS Herman A. Bruson and John W. Kroeger, Philadelphia, Pa., assignors to Riihm & Haas Company, Philadelphia, Pa.

No Drawing.

Application October 1, 1938,

Serial No. 232,852

, Claims.

This invention relates to a process for preparing acetylenic alcohols, more particularly ditertiary acetylenic glycols, and deals with an improved method for obtaining these alcohols in high yields without danger of explosion.

Certain alcohols have heretofore been prepared from the reaction of ketones on alkali metal acetylides in liquid ammonia. But such methods make it necessary to work in complicated apparatus at low temperatures with the consequent hazards and difliculties inherent in such operations. Acetylenic ditertiary glycols, as well as acetylenic monohydric alcohols, have also been made by reacting certain ketones in the presence of alkali metal hydroxides with very finely divided calcium carbide. To accomplish this reaction it has previously been necessary to grind the calcium carbide of commerce in a ball mill with ether until the calcium carbide was ground so extremely fine that it would rapidly react.

The reaction of the carbide with the ketone and alkali metal hydroxide was carried out in a subsequent step at a low temperature. Under these conditions yields as high as 50 to 70% of theory have been obtained in a few cases.

The preliminary grinding of calcium carbide with or without an inert liquid in a ball mill is, however, extremely dangerous, particularly if air or traces of moisture are present. If ether is employed as the inert grinding medium, the process is still more dangerous, since sufiicient heat is developed to boil the ether and build up pressure. Particularly violent explosions have occurred in attempting to repeat this process on a larger scale, even in the presence of higher boiling liquids than ether.

The object of this invention is to provide, without the above dangers, a method whereby ketones can be commercially reacted with calcium carbide to form acetylenic alcohols in high yields, and to eliminate the preliminary grinding of the carbide by itself or with a liquid.

We have discovered a relatively safe method of reacting calcium carbide, an alkali metal hydroxide or its equivalent and a ketone. The reaction is carried out in an inert liquid medium in any apparatus which permits the grinding of the reactants together. If desired, the reaction mixture may be cooled by external means or the temperature of the reacting materials in the inert medium may be controlled by the rate of addition of the ketone. When the reaction is complete, the resulting products are hydrolyzed and the acetylenic alcohols separated by any suitable method. High yields are thus obtained without danger of explosion, even if the reagents or solvents contain moisture.

We have found that ketones will react gradually and smoothly with calcium carbide and a solid alkali metal hydroxide in an inert liquid medium if relatively coarse calcium carbide is used at the start and the carbide is gradually broken up into finer and finer particles in the reaction mixture. Our experiments have shown that coarse carbide is relatively unreactive and that it does not react until it reaches the proper degree of subdivision. Safety in securing the proper state of subdivision, however, results only when the carbide is allowed to react with another reagent as rapidly as it reaches a reactive state. By this means it is possible to control the reaction. Continuous grinding also insures that fresh surfaces of calcium carbide and solid alkali are presented thus hastening the reaction, preventing side reactions, making available all of the carbide, and allowing high yields of the products desired.

By this method the reaction can be carried out in the usual type of jacketed, upright, stationary kettle, equipped with a vertical anchor-type or other suitable stirrer and with a reflux condenser open to the air. This kettle is filled about oneiourth full of steel balls, pellets, or blocks, and to about one-half full of the carbide, alkali metal hydroxide and inert liquid medium. The stirrer is started and the ketone addition then begun. With the lower ketones the temperature may be regulated by cooling water in the jacket so as not to exceed about C. With the higher solid ketones, a temperature of 50 to C. may be used. These are not to be interpreted as limiting temperatures since with less reactive ketones still higher temperatures may be used. An inert gas, such as nitrogen, may be continuously passed into the charge. As the stirring proceeds, the steel balls swirl about and pound the carbide and alkali into fine powders, which react with the entering ketone smoothly and gradually as fast as the state of subdivision becomes fine enough. The reaction is usually complete in about 4 to 48 hours, depending upon the size of the charge, the nature of the ketone, the design and speed of the stirrer, the quantity and size of the steel pellets, and the initial coarseness of the carbide. In order to save time, it is advantageous to utilize the commercially available 2035 mesh calcium carbide which is initially relatively non-reactive in the process.

We have'found that potassium hydroxide gives higher yields than does sodium hydroxide. Flake caustic is most convenient to use. The reaction appears to require at least one mol of alkali metal hydroxide per mol of calcium carbide. Good yields are also obtained using two mols of potassium hydroxide per mol of calcium carbide. In the calculation of proportions allowance is made for the impurities present in the commercial carhide.

The reaction to form a monohydric acetylenic alcohol requires at least one mol of ketone per mol of calcium carbide and to form a glycol at least two mols of ketone per mol of calcium carbide. The reaction, therefore, is not limited to one particular proportion of reactants. Although an excess of ketone may be used, for reasons of economy and convenience it is desirable to keep the proportions close to the theoretical demands. The proportions as indicated may be adjusted in accordance with the desire to produce more or less of the monohydric alcohol or of the ditertiary glycol. But the proportion of reactants as such does not determine the proportion of these products which result-from the reaction. The yield of monohydric alcohols is greater at relatively lower temperatures and conversely the yield of ditertiary glycols is relatively higher as the reaction is maintained in the upper range of suitable temperatures.

Suitable liquids to serve as inert media and solvents are benzene, toluene, xylene, petroleum naphtha or other hydrocarbons, aliphatic or aromatic ethers, particularly the higher homologues, or other liquids which are inert to calcium carbide and alkali. These liquids may be used individually or as mixtures. It is frequently found desirable to add the liquids in more than one step and the ketone may be added, dissolved or dispersed in the inert medium, if it is so desired.

After all the ketone has been reacted, the mixture may be hydrolyzed with water or an acid. In the examples hydrochloric acid is used as an economical and convenient reagent, which is illustrative of the process, but any other acids such as formic, acetic, sulfuric, oxalic, etc. or carbon dioin'de may be used to destroy the alkali and/or remove the calcium hydroxide formed.

The reaction is applicable, as far as it is known, to all ketones which are not decomposed by strong alkalies in the process. It is operative with aliphatic ketones, such as acetone, methyl ethyl ketone, and higher aliphatic ketones such as methyl propyl ketones, methyl butyl ketones, methyl amyl ketones, methyl hexyl ketone, methyl dodecyl ketone, methyl octadecyl ketone, diethyl ketone, ethyl propyl ketone, methyl heptenone, etc.; with arylaliphatic ketones, such as acetophenone, propiophenone, butyrophenone, decanoylbenzene, stearophenone, benzyl methyl ketone, etc.; aromatic ketones, such as benzophenone, benzonaphthone, benzoyl anthracene, benzoyl phenanthrene, etc.; heterocyclic ketones, such as isatin and N-alkyl piperidones; and cycloaliphatic or alicyclic ketones, such as camphor, cyclohexanone, cyclohexenones, methyl cyclohexanone, butyl cyclohexanone, isophorone,

etc.

Although in the preferred form of this invention a kettle m'th vertical rotating stirrer, which swirls the steel pellets around upon the carbide, is desirable, nevertheless, the reaction can be carried out in any suitably agitated kettle or mixing apparatus capable of eife'cting comminution of the carbide in an inert liquid medium while the carbide is simultaneously being reacted with the ketone and alkali metal hydroxide at the time of such comminution.

The following examples illustrate this invention, the parts being by weight unless otherwise indicated.

Example 1 In a three-neck, round-bottom vessel of three liter capacity, fitted with a dropping funnel, a

thermometer, a reflux condenser, and a vertical steel shaft acting as a stirrer, having attached at its lower end a piece of bicycle chain about four inches long, fastened at its center to the shaft, so as to sweep the bottom of the flask and conform to its contour, there was placed a mixture consisting of g. (1 mol) of calcium carbide (80% purity; 2035 mesh), 112 g. of powdered potassium hydroxide (2 mols), 320 g. of benzene, and 110 .cc. of small steel balls ranging in size from 6" to A diameter. The stirrer was rotated at 250 R. P. M., causing the steel balls to swirl about rapidly and gradually comminute the carbide and alkali. At the same time, addition of 29 g. of acetone was gradually made and stirring continued for about 18 hours. The thick paste obtained was then thinned with g. of benzene and 116 g. of acetone added very slowly with continual agitation, so that the temperature remained below 50 C. No external cooling was used, the temperature being regulated between 25 and 35 C. by the rate of addition of the acetone. The total stirring time was 47 hours.

The product was hydrolyzed by adding slowly, with external cooling, 450 g. of concentrated hydrochloric acid. The mixture was filtered, and the solid residue was extracted with hot acetone. The combined extract and oil layer was then distilled to recover the solvent. The residue was fractionally distilled under reduced pressure, yielding 127 g. of the crystalline acetylenic glycol and boiling at -125 C./13 mm., having the formula After recrystallization from petroleum ether the compound melted at 94 to 95 C. The yield of acetylenic glycol was 89.5% of theory, based on the carbide and about 5% of the monohydric acetylenic alcohol was found. In a similar experiment, where the potassium hydroxide was .replaced by sodium methylate, the yield of acetylenic glycol was 32%. Calcium hydroxide was not effective.

Example 2 A mixture consisting of 80 g. of calcium carbide (20 mesh; 80% purity), 112 g. of potassium hydroxide (flake), 400 cc. of benzene, and 200 cc. of small steel balls was placed in a round-bottom vessel equipped as in.Example 1, and stirred while g. of methyl-n-hexyl ketone was added dropwise during three hours. Another 160 g. of methyl hexyl ketone was added during the course of 24 hours, with constant stirring. After a total of 96 hours of stirring at 25-35" C., the paste obtained was thinned with 200 cc. of benzene and decomposed with concentrated hydrochloric acid till faintly acid. The oil layer was separated, washed with water, and the benzene was steamdistilled oif. The residue was vacuum distilled at 5 mm. The product came over between 160- 200 C./5 mm., as a pale yellow oil which solidified to a waxy, crystalline mass. Yield was 265 g. of acetylenic glycol or 94% of theory, based on the carbide. Upon redistillation, it boiled at 169 C./5 mm. Its formula is Recrystallization from petroleum ether gave white needles of the compound, M. P. 90-91" C.

Under similar conditions methyl amyl ketone gave an 80% yield of a crystalline glycol, B. P. 151 C./4 mm. and also some monohydric alcohol.

Example 3 A mixture consisting of 80 parts of calcium carbide (20-30 mesh; 80% purity), 112 par-ts of powdered potassium hydroxide, 400 parts of henzene, and 500 parts of steel balls was placed in a vessel fitted with an anchor-type stirrer, and rapidly swirled about while 216 parts of methyl ethyl ketone was gradually added during seven hours. The temperature was held at 25 C, by external cooling. Stirring was continued for 24 hours, during which time 350 par-ts of additional benzene was added to thin out the pas-te'which had formed. The reaction mixture was then hydrolyzed with concentrated hydrochloric acid till acidic to Congo red indicator. The organic layer was separated, filtered, and combined with benzene washings of the steel balls. Upon distillation, a quantitative yield of the acetylenic glycol having the formula was obtained as a crystalline mass boiling at about 120-130 C./12 mm. After recrystallization from diisobutylene the compound melted at I Example 4 A mixture consisting of 40 parts of calcium carbide (20'25 mesh; 80% purity), 56 parts of powdered potassium hydroxide, 182 parts of benzophenone, 1400 parts of benzene and 460 parts of T e" steel balls was rapidly swirled about in a round-bottom vessel for 146 hours. The product Was hydrolyzed with hydrochloric acid and filtered. The crystalline product was separated from the steel balls by means of hot toluene and combined with the benzene filtrate. The hydrocarbons were removed by distillation, leaving the crude crystalline product which, after one recrystallization from toluene, melted at 193-l95 C. (uncorrected) and consisted of the compound CCECC CsHs H OH CaH5 The yield was practically quantitative.

Example 5 A mixture of 139 parts of acetophenone, 40 parts of calcium carbide, 56 parts of powdered potassium hydroxide, 350 parts of benzene, and 500 parts of steel pellets was stirred for 44 hours in a round-bottom, 3-liter flask at 25-30 C. The product was worked up as in Example 4 and isolated by distillation in vacuo. The yield of glycol was 70% of theory of the compound having the formula After one recrystallization from toluene the compound, 2,5--diphenylhexin-3-diol-2,5, melted at 1354'40" C. (mixture of isomers).

Similarly, methyl-pl-naphthyl ketone gives the corresponding acetylenic glycol, M. P. 146-154 C. (mixture of isomers).

Example 6 A mixture consisting of parts of calcium carbide (80% purity; 20-35 mesh), 112 parts of powdered potassium hydroxide, 450 parts of 1%" steel balls, and 330 parts of camphor in 350 parts of benzene was stirred in a 3-liter round-bottom flask for '7 days. The paste thus obtained was thinned with 350 parts of benzene, neutralized with concentrated hydrochloric acid, and filtered. The solid Was extracted with hot benzene and the combined benzene solutions. were distilled. The crystalline product obtained in quantitative yield was recrystallized from aqueous alcohol and then from petroleum ether, giving colorless crystals, M. P. 197-199 C. (uncorrected). It consists of the product having the formula (IJH: (EH3 0 on. I .o-ozco I CHz I CHaCCHa I I CH3C-'CH3 CH2 I CH2 CH2 7 I CH2 CH on Example 7 Charge: Calcium carbide (80% purity; 20-35 mesh) grams 80' Powdered potassium hydroxide grams 112 Steel balls diameter) grams 500 Benzene cubic centimeters 800 The above mixture was stirred rapidly in a round-bottom vessel by means of an anchor-type agitator which almost scraped the bottom, while 216 g. of cyclohexanone was slowly run in. The mixture was stirred for 53 hours at ordinary temperature and then hydrolyzed with dilute hydrochloric acid. The organic layer was filtered hot and allowed to crystallize. The crystalline glycol was filtered ofi and the filtrate evaporated to about 300 cc. On cooling, the remaining glycol crystallized out. The total yield of crystalline glycol, M. P. 101 C., was 190 g. or of theory. It has the formula OH, OH OH om CH2 C!1C:C(|) (352 CH1 CH2 CH2 CH2 CH: CH:

Example 8 Charge: 5-Ethylnonanone-2 grams 55 Potassium hydroxide grams 18.5 Calcium carbide (80% purity; 20-35 mesh) grams 13 Benzene cubic centimeters 200 Steel pellets grams 500 The above reagents were charged into the apparatus described in Example 1, and stirred for hours at 20-25 C. The resulting suspension was made distinctly acidic with dilute hydrochloric acid, then the organic layer was filtered from a small amount of carbon and washed with water. The acetylenic glycol was obtained by fractionation, as a thick yellow oil boiling from RIO-230 C./8 mm. Yield 40% of theory. The boiling point of the glycol was 210 C./8 mm. It has the formula In' addition to the acetylenic glycol, the acetylenic tertiary monohydric alcohol was obtained as a pale yellow, limpid oil boiling from 100-130 C./8 mm. (B. P. 120 C./8 mm.). Yield 60% of theory. The compound gave a white, insoluble silver salt with a. solution of silver nitrate in ammoniacal alcohol indicating that it had the following formula CzIIs Charge:

Stearophenone grams 55 Calcium carbide grams 6.4 Potassium hydroxide grams 9.0 Benzene cubic centimeters" 500 Steel pellets grams 200 (a) The mixture was stirred for 216 hours at -25 C. When the product was worked up as in previous examples, a soft, brown wax was obtained by evaporating the solvent. This wax was dissolved in petroleum ether (B. P. 60-100 C.), and the solution was refluxed with Norite. After filtering and cooling the filtrate, the unchanged stearophenone crystallized (M. P. 50-51 C.) Evaporation of the mother liquors gave the acetylenic glycol which was a yellow, waxy solid melting at 37'.

(b) Under similar conditions methyl isobutyl ketone gave 2,4,7,9-tetramethyldecin-5-diol-4,7, B. P. 150 C./l7 mm., M. P. 59-60 C.

(c) p-Phenyl-isobutyl methyl ketone in the same way gave an acetylenic glycol, B. P. 228 C./6 mm.

The mixture was stirred for 70 hours at -30 C. and the thick paste which resulted was hydrolyzed by slowly adding 450 parts of concentrated hydrochloric acid The organic layer was illtered. washed with water, and distilled. The fraction boiling from 180-160 C./1 mm. (240 parts yield) was a yellow syrup which crystallized Ha C CH:

CHz

I CCEC-G C-CH:

BC BC The method for producing acetylenic alcohols described herein eliminates the dangerous step of grinding calcium carbide by itself or under an anhydrous solvent, such as ether, with the concomitant risks involved with. such a hazardous solvent. It makes it unnecessary to work with completely anhydrous reagents. It allows the use of a wide variety of solvent media and a large range of ketones. It is particularly advantageous when high melting, diiiicultly soluble ketones are used. It has an important economic advantage in high yields. The development of this process makes it possible to produce acetylenic monohydric alcohols and glycols on a practical commercial basis and makes available the higher alkyl and aryl as well as olefinic acetylenic alcohols.

Furthermore, although acetylenic glycols are predominantly obtained, acetylenic monohydric alcohols are usually also obtained and by adjustment of conditions may be produced in relatively larger proportion, if so desired.

The acetylenic alcohols obtained by the process set forth herein, particularly the acetylenic glycols, are useful intermediates for the preparation of acetylenic diolefines by dehydration. These diolefines can be polymerized to resins. The acetylenic alcohols may also be partially or completely hydrogenated to the corresponding olefinic or saturated alcohols. For instance, upon catalytic hydrogenation in the presence of Raney nickel at 60-100 C. and to 200 lbs. per sq. in. pressure, the acetylenic glycols are reduced to the saturated 1,4-ditertiary glycols which are useful intermediates for the preparation of tetrahydrofuranes by ring closure. The acetylenic alcohols as well as their derivatives are high boiling solvents for oils, fats, resins and waxes. The 1,4- ditertiary glycols may, furthermore, be condensed with aromatic compounds by condensing agents of acidic character to yield new ar-tetrahydronaphthalene derivatives useful as dyestufi intermediates.

The specification and examples given above, while disclosing the nature of our invention and presenting typical results showing its wide application for the formation of monohydric acetylenic alcohols and ditertiary acetylenic alcohols, are not to be considered as imposing limitations thereon.

We claim:

1. The process of preparing acetylenic alcohols which comprises gradually comminuting relatively coarse calcium carbide in the presence of an inert liquid medium, an alkali metal hydroxide, and a ketone, hydrolyzing the reaction mixture, and separating the alcohols.

2. The process of preparing acetylenic alcohols which comprises gradually comminuting relatively coarse calcium carbide in the presence of an inert liquid medium and an alkali metal hydroxide while adding to said mixture a ketone at such rate that the mixture is maintained at reaction temperature, hydrolyzing the reaction mixture, and separating the alcohols.

3. In the process of preparing acetylenic alcohols from ketones, calcium carbide and an alkali metal hydroxide, the step which comprises the gradual comminution of initially relatively coarse calcium carbide in the presence of the ketone, the alkali metal hydroxide and an inert liquid medium, whereby the reaction of the carbide with the alkali metal hydroxide and the ketone is controlled.

4. In the process of preparing an acetylenic glycol of the formula where R and R1 are hydrocarbon radicals, the

improvement which comprises comminuting in an inert medium relatively coarse calcium carhide in the presence of a ketone of the formula R-CO-R1 and of an alkali metal hydroxide.

5. In the process of preparing an acetylenic monohydric alcohol of the formula \CCECH where R and R1 are hydrocarbon radicals, the improvement which comprises comminuting in an inert medium relatively coarse calcium carbide in the presence of a ketone of the formula R-CO-Ri 2 and of an alkali metal hydroxide.

HERMAN A. BRUSON. JOHN W. KROEGER. 

